Methods of preparing photovoltaic modules

ABSTRACT

Methods of preparing photovoltaic modules, as well as related components, systems, and devices, are disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. §120, this application is a continuation of andclaims priority to U.S. application Ser. No. 12/503,721, filed Jul. 15,2009, now U.S. Pat. No. 7,932,124, granted Apr. 26, 2011, which in turnclaims priority to U.S. Provisional Application Ser. No. 61/081,100,filed Jul. 16, 2008, and U.S. Provisional Application Ser. No.61/147,515, filed Jan. 27, 2009. The contents of the parent applicationsare hereby incorporated by reference.

TECHNICAL FIELD

This invention relates to methods of preparing photovoltaic modules, aswell as related components, systems, and devices.

BACKGROUND

Photovoltaic cells are commonly used to transfer energy in the form oflight into energy in the form of electricity. A typical photovoltaiccell includes a photoactive material disposed between two electrodes.Generally, light passes through one or both of the electrodes tointeract with the photoactive material, thereby generating chargecarriers (i.e., electrons and holes). As a result, it is desirable forat least one of the electrodes to be at least semi-transparent.

SUMMARY

In one aspect, this disclosure features a method that includes forming afirst multilayer device containing a first electrically conductive layerand a photoactive layer on a substrate and, after forming the firstmultilayer device, treating the first electrically conductive layer toform a plurality of electrodes, thereby converting the first multilayerdevice into a first photovoltaic cell. The first electrically conductivelayer is between the photoactive layer and the substrate.

In another aspect, this disclosure features a method that includesforming a first electrically conductive layer, a photoactive layer, anda hole carrier layer on a substrate, and treating the first electricallyconductive layer, the photoactive layer, and the hole carrier layer toform a plurality of discrete multilayer devices, each of which containsa first electrode, a photoactive layer, and a hole carrier layer. Thefirst electrically conductive layer is between the substrate and thephotoactive layer and the photoactive layer is between the firstelectrically conductive layer and the hole carrier layer.

In still another aspect, this disclosure features a method that includesforming a multilayer device containing a first electrically conductivelayer and a second layer on a substrate, and after forming themultilayer device, forming the first electrically conductive layer intoa plurality of discrete electrodes. The first electrically conductivelayer is between the substrate and the second layer.

Embodiments can include one or more of the following features.

The method can further include forming a second multilayer device on thesubstrate before treating first electrically conductive layer. Thesecond multilayer device can include a first electrically conductivelayer and a photoactive layer. The first and second electricallyconductive layers of the first and second multilayer devices can be thesame layer. Treating the first electrically conductive layer can convertthe second multilayer device into a second photovoltaic cell.

Each of the first and second multilayer devices can further include ahole carrier layer and/or a second electrically conductive layer.

Treating the first electrically conductive layer can be carried out bylaser ablation or mechanical scribing.

Treating the first electrically conductive layer can form a cavity(i.e., an empty space) in the first electrically conductive layerbetween the first and second multilayer devices.

The method can further include disposing a first insulator between thefirst and second photovoltaic cells after treating the firstelectrically conductive layer. In some embodiments, at least a portionof the first insulator is disposed in the cavity between the first andsecond multilayer devices. In some embodiments, the method can furtherinclude disposing an electrically conductive material over the firstinsulator, thereby electrically connecting the first and secondphotovoltaic cells. In certain embodiments, the second electricallyconductive layer of the first photovoltaic cell is electricallyconnected to the first electrically conductive layer of the secondphotovoltaic cell through the electrically conductive material.

The method can further include disposing a first insulator beforetreating the first electrically conductive layer. In some embodiments,the first insulator prevents debris formed during treating the firstelectrically conductive layer from interacting with the first and secondphotovoltaic cells. In such embodiments, the method can further includedisposing a second insulator after treating the first electricallyconductive layer. At least a portion of the second insulator can bedisposed in the cavity between the first and second multilayer devices.In some embodiments, the method further includes disposing anelectrically conductive material over the first and second insulators,thereby electrically connecting the first and second photovoltaic cells.In certain embodiments, the second electrically conductive layer of thefirst photovoltaic cell is electrically connected to the firstelectrically conductive layer of the second photovoltaic cell throughthe electrically conductive material.

Treating the first electrically conductive layer can be carried out onthe first electrically conductive layer at a location beneath the firstinsulator. In such embodiments, treating the first electricallyconductive layer can be carried out by irradiation with a laser. Forexample, the laser can be irradiated from the side of the substrate thatis opposite to the side on which the first multilayer device isdisposed. In some embodiments, the method can further include disposingan electrically conductive material over the first insulator, therebyelectrically connecting the first and second photovoltaic cells. Incertain embodiments, the second electrically conductive layer of thefirst photovoltaic cell is electrically connected to the firstelectrically conductive layer of the second photovoltaic cell throughthe electrically conductive material.

The method can further include disposing a first insulator beforetreating the first electrically conductive layer. In some embodiments,an electrically conductive material is also disposed over the firstinsulator before treating the first electrically conductive layer. Insome embodiments, treating the first electrically conductive layer iscarried out on the first electrically conductive layer at a locationbeneath the first insulator. In some embodiments, treating the firstelectrically conductive layer is carried out by irradiation with a laserfrom the side of the substrate that is opposite to the side on which thefirst multilayer is disposed. In some embodiments, the electricallyconductive material forms a second electrically conductive layer of thefirst photovoltaic cell and is electrically connected to the firstelectrically conductive layer of the second photovoltaic cell.

Treating the first electrically conductive layer, the photoactive layer,and the hole carrier layer can be carried out by irradiation with afirst laser (e.g., having a wavelength absorbed by the firstelectrically conductive layer, the photoactive layer, and the holecarrier layer). In some embodiments, the method can further includeirradiating a second laser (e.g., having a wavelength absorbed by thephotoactive layer and hole carrier layer in each multilayer device) tothe photoactive layer and hole carrier layer in each multilayer device,thereby forming a cavity in the photoactive layer and hole carrier layerin each device. In some embodiments, the method further includesdisposing a first insulator between each two discrete devices of theplurality of multilayer devices. In such embodiments, the method canfurther include disposing a second electrically conductive layer overthe first insulator to form a plurality of photovoltaic cells, thesecond electrically conductive layer of one photovoltaic cellelectrically connecting to the first electrically conductive layer of aneighboring photovoltaic cell. In some embodiments, the method furtherincludes disposing a second insulator into at least a portion of eachcavity.

The first multilayer device can further include a second electricallyconductive layer supported by the hole carrier layer before treating thefirst electrically conductive layer, the photoactive layer and the holecarrier layer. In some embodiments, the method can further includetreating the second electrically conductive layer to form a plurality ofsecond electrodes, thereby forming a plurality of discrete photovoltaiccells. In such embodiments, treating the first electrically conductivelayer, the photoactive layer, the hole carrier layer, and the secondelectrically conductive layer is carried out by irradiation with a firstlaser (e.g., having a wavelength absorbed by the first and secondelectrically conductive layers, the photoactive layer, and the holecarrier layer). In some embodiments, the method can further includedisposing a first insulator between the discrete cells of the pluralityof photovoltaic cells. In some embodiments, the method can furtherinclude irradiating a second laser to the plurality of photovoltaiccells, thereby forming first and second cavities in the photoactivelayer, the hole carrier layer, and the second electrode of eachphotovoltaic cell. In such embodiments, the method can further includedisposing a third electrically conductive material in at least a portionof the first cavity of a photovoltaic cell, the third electricallyconductive material electrically connecting the first electrode of thephotovoltaic cell and the second electrode of a neighboring photovoltaiccell.

The method can further include disposing a second insulator between thefirst electrically conductive layer and the photoactive layer at alocation the first insulator is to be deposited before irradiating thefirst laser to the first electrically conductive layer, the photoactivelayer, the hole carrier layer, and the second electrically conductivelayer.

The method can form a plurality of photovoltaic cells.

Each of the photovoltaic cells can include a respective electrode of theplurality of discrete electrodes, which can be formed by laser ablationor mechanical scribing.

The plurality of discrete electrodes can be formed by irradiating alaser to the first electrically conductive layer. In some embodiments,the laser is irradiated to the first electrically conductive layereither from the side of the substrate on which the first electricallyconductive layer and the second layer are disposed or its opposite side.In some embodiments, the laser reaches the first electrically conductivelayer by passing through the substrate or the second layer (e.g., notsubstantially absorbed by the substrate or the second layer). In someembodiments, the irradiation forms a plurality of cavities so that eachdiscrete electrode is separated from another discrete electrode by acavity.

The laser can be a fiber laser.

The laser can have a wavelength ranging from about 200 nm to about 1,600nm (e.g., about 1,064 nm).

The second layer can be a hole blocking layer, a photoactive layer, ahole carrier layer, or a second electrically conductive layer.

Forming the multilayer device can further include forming a holeblocking layer, a hole carrier layer, and a second electricallyconductive layer, in which the hole blocking layer is between the firstelectrically conductive layer and the photoactive layer, the photoactivelayer is between the hole blocking layer and the hole carrier layer, andthe hole carrier layer is between the photoactive layer and the secondelectrically conductive layer.

Forming the multilayer device can further include forming a hole carrierlayer, a hole blocking layer, and a second electrically conductivelayer, in which the hole carrier layer is between the first electricallyconductive layer and the photoactive layer, the photoactive layer isbetween the hole carrier layer and the hole blocking layer, and the holeblocking layer is between the photoactive layer and the secondelectrically conductive layer.

Embodiments can provide one or more of the following advantages.

Without wising to be bound by theory, it is believed that patterning thefirst electrically conductive layer to form bottom electrodes afterphotoactive layers of the photovoltaic cells are formed on top of thebottom electrodes could minimize short circuit between two neighboringphotovoltaic cells.

Without wishing to be bound by theory, it is believed that disposing aninsulator into at least a portion of a cavity between two neighboringphotovoltaic cells can minimize short circuit of the bottom electrodesof these two cells. Further, without wishing to be bound by theory, itis believed that disposing an insulator between two photovoltaic cellscan effectively minimize short circuit of these two cells resulted fromthe debris formed during the treatment of an electrically conductivelayer.

Without wishing to be bound by theory, it is believed that disposing anadditional insulator before treating an electrically conductive layercan more effectively protect the photovoltaic cells formed in a finalmodule from short circuit resulted from any debris generated during thetreatment process.

In some embodiments, two discrete photovoltaic cells can be formed bytreating (e.g., by laser ablation or mechanical scribing) anelectrically conductive material in an electrically conductive layer ata location beneath an insulator between the two cells into anelectrically non-conductive material or a cavity. Without wishing to bebound by theory, it is believed that an advantage of this approach isthat short circuit between the two photovoltaic cells can be minimizedbecause essentially no debris is formed during the treatment process.

Other features and advantages of the invention will be apparent from thedescription, drawings, and claims.

DESCRIPTION OF DRAWINGS

FIG. 1( a) is a first step in a first embodiment of forming aphotovoltaic module.

FIG. 1( b) is a second step in the first embodiment of forming aphotovoltaic module.

FIG. 1( c) is a third step in the first embodiment of forming aphotovoltaic module.

FIG. 2( a) is a first step in a second embodiment of forming aphotovoltaic module.

FIG. 2( b) is a second step in the second embodiment of forming aphotovoltaic module.

FIG. 2( c) is a third step in the second embodiment of forming aphotovoltaic module.

FIG. 3( a) is a first step in a third embodiment of forming aphotovoltaic module.

FIG. 3( b) is a second step in the third embodiment of forming aphotovoltaic module.

FIG. 3( c) is a third step in the third embodiment of forming aphotovoltaic module.

FIG. 4( a) is a first step in a fourth embodiment of forming aphotovoltaic module.

FIG. 4( b) is a second step in a fourth embodiment of forming aphotovoltaic module.

FIG. 5( a) is a first step in a fifth embodiment of forming aphotovoltaic module.

FIG. 5( b) is a second step in the fifth embodiment of forming aphotovoltaic module.

FIG. 5( c) is a third step in the fifth embodiment of forming aphotovoltaic module.

FIG. 5( d) is a fourth step in the fifth embodiment of forming aphotovoltaic module.

FIG. 6( a) is a first step in a sixth embodiment of forming aphotovoltaic module.

FIG. 6( b) is a second step in the sixth embodiment of forming aphotovoltaic module.

FIG. 6( c) is a third step in the sixth embodiment of forming aphotovoltaic module.

FIG. 6( d) is a fourth step in the sixth embodiment of forming aphotovoltaic module.

FIG. 6( e) is a fifth step in the sixth embodiment of forming aphotovoltaic module.

FIG. 7( a) is a first step in a seventh embodiment of forming aphotovoltaic module.

FIG. 7( b) is a second step in the seventh embodiment of forming aphotovoltaic module.

FIG. 7( c) is a third step in the seventh embodiment of forming aphotovoltaic module.

FIG. 7( d) is a fourth step in the seventh embodiment of forming aphotovoltaic module.

FIG. 7( e) is a fifth step in the seventh embodiment of forming aphotovoltaic module.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

This disclosure relates to methods of preparing photovoltaic modules, aswell as related components, systems, and devices. In some embodiments,photovoltaic modules can be prepared by a general method of (1) formingat least a first multilayer device on a substrate, the first multilayerdevice containing at least a first electrically conductive layer and aphotoactive layer; and (2) after forming the first multilayer device,treating the first electrically conductive layer to form a plurality ofelectrodes, thereby converting the first multilayer device into a firstphotovoltaic cell or a plurality of photovoltaic cells including a firstphotovoltaic cell.

In some embodiments, the general method can include first forming aplurality of multilayer devices including a first multilayer device on asubstrate. The first multilayer device can include a first electricallyconductive layer (which later forms a bottom electrode), a photoactivelayer, a hole carrier layer and a top electrode sequentially disposed onthe substrate. The first electrically conductive layer can then betreated (e.g., by laser ablation or mechanical scribing) to form abottom electrode, thereby converting the first multilayer device into afirst photovoltaic cell.

In some embodiments, the general method can include forming a firstmultilayer device containing a first electrically conductive layer, aphotoactive layer, and a hole carrier layer sequentially disposed on asubstrate. The first multilayer device can then be treated (e.g., bylaser ablation or mechanical scribing) to form a plurality of discretemultilayer devices, each of which includes a bottom electrode, aphotoactive layer, and a hole carrier layer. These discrete multilayerdevices can then be configured (e.g., after forming top electrodes) toform discrete photovoltaic cells. The first multilayer device can alsoinclude a second electrically conductive layer disposed on the holecarrier layer so that discrete photovoltaic cells can be formed upontreating the first multilayer device (e.g., by laser ablation).

FIG. 1 shows a first embodiment of the general method described above.This embodiment forms a photovoltaic module 100 that contains aplurality of photovoltaic cells (e.g., organic photovoltaic cells). Eachphotovoltaic cell in photovoltaic module 100 contains a substrate 110, abottom electrode 120, a photoactive layer 130 (e.g., containing anelectron donor material and an electron acceptor material), a holecarrier layer 140, and a top electrode 150. An insulator 160 is disposedbetween two neighboring photovoltaic cells. The top electrode of onephotovoltaic cell is electrically connected to the bottom electrode of aneighboring photovoltaic cell via an interconnecting electricallyconductive material 170.

Photovoltaic module 100 shown in FIG. 1 can be prepared by three mainsteps as follows:

First, as shown in FIG. 1( a), after a first electrically conductivelayer 122 (which later forms bottom electrodes 120) is disposed onsubstrate 110, a plurality of photoactive layers 130, hole carrierlayers 140, and top electrodes 150 are sequentially disposed on thefirst electrically conductive layer to form a plurality of multilayerdevices. The distance between two neighboring multilayer devices thusformed (e.g., the distance between the two photoactive layers of twoneighboring multilayer devices) can be at least about 100 μm (e.g., atleast about 200 μm, at least about 500 μm, or at least about 1,000 μm)or at most about 5 mm (e.g., at most about 3 mm, at most about 1 mm, orat most about 0.5 mm).

Second, as shown in FIG. 1( b), first electrically conductive layer 122can be treated to form a plurality of bottom electrodes 120, therebyforming a plurality of discrete photovoltaic cells that are electricallyisolated from each other. This step is also known as patterning firstelectrically conductive layer 122. For example, first electricallyconductive layer 122 can be treated to form a cavity 125 (i.e., an emptyspace) between every two neighboring multilayer devices. Typically,cavity 125 completely separates two neighboring multilayer devices toform two discrete photovoltaic cells (e.g., without any short circuitingbetween two neighboring cells). In some embodiments, cavity 125 can havea length of at least about 1 μm (e.g., at least about 10 μm, at leastabout 50 μm, or at least about 100 μm) or at most about 500 μm (e.g., atmost about 300 μm, at most about 100 μm, or at most about 50 μm). Insome embodiments, the depth of cavity 125 is similar to or slightlylarger than the thickness of first electrically conductive layer 122.

Generally, first electrically conductive layer 122 can be treated by anysuitable methods. Examples of such treating methods include laserablation and mechanical scribing, both of which are known in the art. Insome embodiments, when laser ablation is used to treat firstelectrically conductive layer 122, the laser can have a wavelengthabsorbed by the material used to make first electrically conductivelayer 122. In some embodiments, the laser can have a wavelength in theinfrared region (e.g., ranging from about 750 nm to about 1,600 nm), inthe visible light region (e.g., ranging from about 400 nm to about 750nm), or in the ultraviolet region (e.g., ranging from about 200 nm toabout 400 nm). For example, when first electrically conductive layer 122includes indium tin oxide, the laser used to treat this layer can have awavelength of 1,064 nm. In some embodiments, the laser is a fiber laser.

Without wising to be bound by theory, it is believed that patterningfirst electrically conductive layer 122 to form bottom electrodes afterphotoactive layers of the photovoltaic cells are formed on top of layer122 could minimize short circuit between two neighboring photovoltaiccells.

Finally, as shown in FIG. 1( c), insulators 160 can be disposed betweenevery two neighboring discrete photovoltaic cells to electricallyinsulate each cell from other cells. In some embodiments, at least aportion of insulator 160 can be disposed in at least a portion of cavity125 (e.g., the entire cavity) between two neighboring photovoltaiccells. Without wishing to be bound by theory, it is believed thatdisposing insulator 160 into at least a portion of cavity 125 canminimize short circuit of the bottom electrodes of two neighboringphotovoltaic cells. Further, without wishing to be bound by theory, itis believed that disposing insulator 160 between two photovoltaic cellscan effectively minimize short circuit of these two cells resulted fromthe debris generated during the treatment of first electricallyconductive layer 122.

In general, insulator 160 can be made of any suitable insulatingmaterials, such as polymers prepared from monomeric materials such asamines, acrylates, epoxies, urethanes, or combinations thereof. Examplesof suitable amines include di, tri, or multifunctional amines, such asJeffamines or polyethyleneimines. Examples of suitable epoxides includemono, di, tri, or multifunctional epoxides, such as glycidol, biphenoldiepoxides, or 1,3-propane diglycidyl epoxide. These monomeric materialscan be either coated on a substrate from a solvent or coated on asubstrate directly without using a solvent when they are in the form ofa liquid at room temperature. In some embodiments, the monomericmaterials (e.g., amines and epoxides) can be mixed, coated on asubstrate, and thermally treated to produce transparent or translucentpolymers as an insulator. Alternatively, a photoinitiator can be addedto a mixture of epoxides (with or without a solvent). After the mixturewas coated on a substrate and dried, it can be irradiated (e.g., with aUV light) to produce a tough flexible network of polymers.

After insulators 160 are disposed, interconnecting electricallyconductive material 170 can then be deposited over insulator 160 betweentwo neighboring photovoltaic cells, thereby electrically connecting thetop electrode of a photovoltaic cell with the bottom electrode of aneighboring photovoltaic cell. Photovoltaic module 100 thus formedinclude a plurality of photovoltaic cells that are electricallyconnected in series.

Substrate 110 is generally formed of a transparent material. As usedherein, a transparent material refers to a material that, at thethickness used in a photovoltaic cell, transmits at least about 70%(e.g., at least about 75%, at least about 80%, at least about 85%, or atleast about 90%) of incident light at a wavelength or a range ofwavelengths (e.g., from about 350 nm to about 1,000 nm) used duringoperation. Exemplary materials from which substrate 110 can be formedinclude polyethylene terephthalates, polyimides, polyethylenenaphthalates, polymeric hydrocarbons, cellulosic polymers,polycarbonates, polyamides, polyethers and polyether ketones. In certainembodiments, the polymer can be a fluorinated polymer. In someembodiments, combinations of polymeric materials are used. In certainembodiments, different regions of substrate 110 can be formed ofdifferent materials. Examples of suitable substrates are described incommonly-owned co-pending U.S. Patent Application Publication Nos.2004-0187911 and 2006-0090791, the entire contents of which are herebyincorporated by reference.

In some embodiments, bottom electrode 120, top electrode 150, andelectrically conductive material 170 can be formed of any suitableelectrically conductive material. Examples of suitable electricallyconductive materials include electrically conductive metals,electrically conductive alloys, electrically conductive polymers, andelectrically conductive metal oxides. Exemplary electrically conductivemetals include gold, silver, copper, aluminum, nickel, palladium,platinum, and titanium. Exemplary electrically conductive alloys includestainless steel (e.g., 332 stainless steel, 316 stainless steel), alloysof gold, alloys of silver, alloys of copper, alloys of aluminum, alloysof nickel, alloys of palladium, alloys of platinum and alloys oftitanium. Exemplary electrically conducting polymers includepolythiophenes (e.g., doped poly(3,4-ethylenedioxythiophene) (dopedPEDOT)), polyanilines (e.g., doped polyanilines), polypyrroles (e.g.,doped polypyrroles). Exemplary electrically conducting metal oxidesinclude indium tin oxide (ITO), fluorinated tin oxide, tin oxide andzinc oxide. In some embodiments, the conductive metal oxides describedabove can be doped. In some embodiments, bottom electrode 120, topelectrode 150, and electrically conductive material 170 can include amultilayer material, such as an ITO/metal/ITO material or adielectric/metal/dielectric material. In some embodiments, a combinationof the materials described above can be used.

In some embodiments, bottom electrode 120 and top electrode 150 caninclude a mesh electrode. Examples of mesh electrodes are described incommonly-owned co-pending U.S. Patent Application Publication Nos.2004-0187911 and 2006-0090791, the entire contents of which are herebyincorporated by reference.

In some embodiments, photoactive layer 130 can include an organicelectron donor material or an organic electron acceptor material.Suitable organic electron donor materials include conjugated polymers,such as polythiophenes (e.g., poly(3-hexylthiophene) (P3HT)) orpoly(phenylene-vinylene)s (PPVs). Suitable organic electron acceptormaterials include fullerenes (e.g., a substituted fullerene such as[6,6]-phenyl C61-butyric acid methyl ester (C61-PCBM) and [6,6]-phenylC71-butyric acid methyl ester (C71-PCBM)). Examples of suitable organicelectron donor or acceptor materials are described in, for example,commonly-owned co-pending U.S. Patent Application Publication Nos.2007-0020526, 2008-0087324, and 2008-0121281, the entire contents ofwhich are hereby incorporated by reference.

In some embodiments, hole carrier layer 140 can include a semiconductivepolymer. Exemplary polymers include polythiophenes, polyfluorenes,polyphenylene vinylenes, polyanilines, and polyacetylenes. In someembodiments, the polymer is formed from thieno[3,4-b]thiophene monomerunits. Examples of commercially available semiconductive polymersinclude H.C. Starck BAYTRON® family of polymers (e.g., PEDOT) and theAir Products® HIL family of polymers. In some embodiments, hole carrierlayer 140 can include a dopant used in combination with a semiconductivepolymer. Examples of dopants include poly(styrene-sulfonate)s, polymericsulfonic acids, or fluorinated polymers (e.g., fluorinated ion exchangepolymers). Other examples of suitable hole carrier materials aredescribed in, for example, commonly-owned co-pending U.S. ProvisionalApplication Publication No. 60/985,006, the entire contents of which arehereby incorporated by reference.

In general, the methods of preparing each layer (e.g., firstelectrically conductive layer 122, photoactive layer 130, hole carrierlayer 140, top electrode 150, insulator 160, and the interconnectingelectrically conductive material 170) in the photovoltaic cellsdescribed in FIG. 1 can vary as desired. In some embodiments, a layercan be prepared by a liquid-based coating process. In certainembodiments, a layer can be prepared via a gas phase-based coatingprocess, such as chemical or physical vapor deposition processes.

The term “liquid-based coating process” mentioned herein refers to aprocess that uses a liquid-based coating composition. Examples of theliquid-based coating composition include solutions, dispersions, orsuspensions. The liquid-based coating process can be carried out byusing at least one of the following processes: solution coating, ink jetprinting, spin coating, dip coating, knife coating, bar coating, spraycoating, roller coating, slot coating, gravure coating, flexographicprinting, and screen printing. Examples of liquid-based coatingprocesses have been described in, for example, commonly-owned co-pendingU.S. Application Publication No. 2008-0006324, the entire contents ofwhich are hereby incorporated by reference.

FIG. 2 shows a second embodiment of the general method described above.Similar to the photovoltaic module shown in FIG. 1, photovoltaic module100 formed in this embodiment contains a plurality of photovoltaiccells, each of which includes a substrate 110, a bottom electrode 120, aphotoactive layer 130, a hole carrier layer 140, and a top electrode150. An insulator 160 and an insulator 165 are disposed between twoneighboring photovoltaic cells. The top electrode of one photovoltaiccell is electrically connected to the bottom electrode of a neighboringphotovoltaic cell via an interconnecting electrically conductivematerial 170.

Photovoltaic module 100 shown in FIG. 2 can be prepared by three mainsteps as follows:

First, as shown in FIG. 2( a), after a first electrically conductivelayer 122 (which later forms bottom electrodes 120) is disposed onsubstrate 110, a plurality of photoactive layers 130, hole carrierlayers 140, and top electrodes 150 are sequentially disposed on firstelectrically conductive layer 122 to form a plurality of multilayerdevices. Unlike the method shown in FIG. 1, a plurality of additionalinsulators 160 are disposed between every two neighboring multilayerdevices before first electrically conductive layer 122 is treated toform a plurality of bottom electrodes. Without wishing to be bound bytheory, it is believed that disposing additional insulators beforetreating first electrically conductive layer 122 can prevents debrisgenerated during treating first electrically conductive layer 122 frominteracting with the photovoltaic cells in the final module 100, therebymore effectively protecting the photovoltaic cells from short circuitresulted from such debris.

Second, as shown in FIG. 2( b), first electrically conductive layer 122can be treated (e.g., by irradiation of a laser from the top of layer122) to form a plurality of bottom electrodes 120, thereby forming aplurality of discrete photovoltaic cells that are electrically isolatedfrom each other. For example, first electrically conductive layer 122can be treated to form a cavity 125 between every two neighboringmultilayer devices. Typically, cavity 125 would completely separate twoneighboring multilayer devices to form two discrete photovoltaic cells(e.g., without any short circuiting between two neighboring cells).Without wishing to be bound by theory, it is believed that, when cavity125 is generated by laser ablation, the material evaporated by the laserablation (i.e., the debris) can be deposited on substrate 110.

Finally, as shown in FIG. 2( c), insulators 165 can be disposed betweenevery two neighboring discrete photovoltaic cells to electricallyinsulate each cell from other cells. In some embodiments, at least aportion of insulator 165 can be disposed in at least a portion of thecavity (e.g., the entire cavity) between two neighboring photovoltaiccells to avoid short circuit of two neighboring bottom electrodes (e.g.,caused by the debris generated during laser ablation). After insulators165 are disposed, interconnecting electrically conductive material 170can be deposited over insulators 160 and 165 between two neighboringphotovoltaic cells, thereby electrically connecting the top electrode ofa photovoltaic cell with the bottom electrode of a neighboringphotovoltaic cell. Photovoltaic module 100 thus formed include aplurality of photovoltaic cells that are electrically connected inseries.

Other characteristics or aspects of the method and photovoltaic moduledescribed in FIG. 2 can be the same as those described in FIG. 1.

FIG. 3 shows a third embodiment of the general method described above.Similar to the photovoltaic module shown in FIG. 1, photovoltaic module100 formed in this embodiment contains a plurality of photovoltaiccells, each of which includes a substrate 110, a bottom electrode 120, aphotoactive layer 130, a hole carrier layer 140, and a top electrode150. An insulator 160 is disposed between two neighboring photovoltaiccells. The top electrode of one photovoltaic cell is electricallyconnected to the bottom electrode of a neighboring photovoltaic cell viaan interconnecting electrically conductive material 170.

Photovoltaic module 100 shown in FIG. 3 can be prepared by three mainsteps as follows:

First, as shown in FIG. 3( a), after a first electrically conductivelayer 122 (which later forms bottom electrodes 120) is disposed onsubstrate 110, a plurality of photoactive layers 130, hole carrierlayers 140, and top electrodes 150 are sequentially disposed on firstelectrically conductive layer 122 to form a plurality of multilayerdevices. Unlike the method shown in FIG. 1, a plurality of insulators160 are disposed between every two neighboring multilayer devices beforefirst electrically conductive layer 122 is treated to form a pluralityof bottom electrodes.

Second, as shown in FIG. 3( b), first electrically conductive layer 122can be treated (e.g., by using laser ablation) at locations beneathinsulators 160 to form a plurality of bottom electrodes 120, therebyforming a plurality of discrete photovoltaic cells that are electricallyisolated from each other. In such an embodiment, the treatment can becarried out by irradiating the bottom of first electrically conductivelayer 122 with a laser at a suitable location beneath insulator 160 of amultilayer device. Without wishing to be bound by theory, it is believedthat the laser can burn up the electrically conductive material at thatlocation and create an ablation cavity, thereby forming electricallyseparated bottom electrodes 120, and that the material evaporated by thelaser ablation (i.e., the debris) can be deposited into insulator 160.In such embodiments, the laser can have a wavelength (e.g., about 1,064nm) primarily absorbed by first electrically conductive layer 122, butnot substantially absorbed by the other layers (such as substrate 110).In some embodiments, first electrically conductive layer 122 can beirradiated with a laser from the top of layer 122. In such embodiments,the laser can have a wavelength (e.g., about 1,064 nm) primarilyabsorbed by first electrically conductive layer 122, but notsubstantially absorbed by insulator 160. Without wishing to be bound bytheory, it is believed that an advantage of treating layer 122 at alocation beneath insulator 160 is that short circuit between twophotovoltaic cells can be minimized because essentially no debris isformed outside the insulating area during the treatment process.

Finally, as shown in FIG. 3( c), interconnecting electrically conductivematerial 170 can be deposited over insulator 160 between two neighboringphotovoltaic cells, thereby electrically connecting the top electrode ofa photovoltaic cell with the bottom electrode of a neighboringphotovoltaic cell. Photovoltaic module 100 thus formed include aplurality of photovoltaic cells that are electrically connected inseries.

Other characteristics or aspects of the method and photovoltaic moduledescribed in FIG. 3 can be the same as those described in FIG. 1.

FIG. 4 shows a fourth embodiment of the general method described above.Photovoltaic module 100 formed in this embodiment contains a pluralityof photovoltaic cells, each of which includes a substrate 110, a bottomelectrode 120, a photoactive layer 130, and a hole carrier layer 140. Aninsulator 160 is disposed between two neighboring photovoltaic cells.The hole carrier layer of one photovoltaic cell is electricallyconnected to the bottom electrode of a neighboring photovoltaic cell viaan interconnecting electrically conductive material 170, which alsoserves as a top electrode of the first photovoltaic cell.

Photovoltaic module 100 shown in FIG. 4 can be prepared by two mainsteps as follows:

First, as shown in FIG. 4( a), after a first electrically conductivelayer 122 (which later forms bottom electrodes 120) is disposed onsubstrate 110, a plurality of photoactive layers 130, hole carrierlayers 140, insulators 160, and interconnecting electrically conductivematerials 170 are sequentially disposed on the first electricallyconductive layer to form a plurality of multilayer devices. Unlike themethod shown in FIG. 1, insulators 160 and interconnecting electricallyconductive materials 170 are disposed between every two neighboringmultilayer devices before first electrically conductive layer 122 istreated to form a plurality of bottom electrodes.

Second, as shown in FIG. 4( b), first electrically conductive layer 122can be treated (e.g., by using laser ablation) at locations beneathinsulators 160 to form a plurality of bottom electrodes 120, therebyforming a plurality of discrete photovoltaic cells that are electricallyisolated from each other. The treatment can be carried out in a mannersimilar to that described in FIG. 3. Photovoltaic module 100 thus formedincludes a plurality of photovoltaic cells that are electricallyconnected in series.

Other characteristics or aspects of the method and photovoltaic moduledescribed in FIG. 4 can be the same as those described in FIG. 1.

FIG. 5 shows a fifth embodiment of the general method described above.Photovoltaic module 100 formed in this embodiment contains a pluralityof photovoltaic cells, each of which includes a substrate 110, a bottomelectrode 120, a photoactive layer 130, and a hole carrier layer 140. Aninsulator 160 and an optional insulator 165 are disposed between twoneighboring photovoltaic cells. The hole carrier layer of onephotovoltaic cell is electrically connected to the bottom electrode of aneighboring photovoltaic cell via an interconnecting electricallyconductive material 170, which also serves as a top electrode of thefirst photovoltaic cell.

Photovoltaic module 100 shown in FIG. 5 can be prepared by four mainsteps as follows:

First, as shown in FIG. 5( a), a first electrically conductive layer122, a layer of a photoactive material (i.e., layer 132), and a layer ofa hole carrier material (i.e., layer 142) are sequentially disposed(e.g., by using a liquid-based coating process) on substrate 110 to forman intermediate article (also referred to herein as “a first multilayerdevice.”).

Second, as shown in FIG. 5( b), the intermediate article can then betreated by a first laser ablation to form a plurality of multilayerdevices, in which first electrically conductive layer 122 forms aplurality of bottom electrodes 120, layer 132 forms a plurality ofphotoactive layers 130, and layer 142 forms a plurality of hole carrierlayers 140. For example, the intermediate article can be treated to forma plurality of first cavities in first electrically conductive layer122, layer 132, and layer 142. The first laser ablation can be carriedout by irradiating the intermediate article with a first laser. In someembodiments, the first laser can have a wavelength that is primarilyabsorbed by first electrically conductive layer 122, layer 132, andlayer 142, but substantially not absorbed by substrate 110. For example,the first laser can have a wavelength in the infrared region (e.g.,about 1064 nm) or ultra-violet region (e.g., about 355 nm).

Third, as shown in FIG. 5( c), the multilayer devices formed in thesecond step above can then be treated by a second laser ablation to forma plurality of second cavities in photoactive layers 130 and holecarrier layers 140. In some embodiments, the second laser can have awavelength that is primarily absorbed by photoactive layer 130 and holecarrier layer 140, but substantially not absorbed by substrate 110 andbottom electrode 120. For example, the second laser can have awavelength in the visible light (e.g., green light) region, such asabout 532 nm. At least a portion of a second cavity can later be filledwith an interconnecting electrically conductive material 170 forelectrically connecting two neighboring photovoltaic cells.

Finally, as shown in FIG. 5( d), a first insulator 160 can be disposedinto a first cavity to electrically separate two neighboring multilayerdevices. Interconnecting electrically conductive material 170 can thenbe disposed over insulator 160 and into at least a portion of a secondcavity to form a top electrode of a photovoltaic cell and toelectrically connect the top electrode of the photovoltaic cell with thebottom electrode of a neighboring photovoltaic cell. Optionally, asecond insulator 165 can be disposed in the second cavity to ensureelectrically insulation and to minimize short circuit between twoneighboring cells. Photovoltaic module 100 thus formed includes aplurality of photovoltaic cells that are electrically connected inseries.

Other characteristics or aspects of the method and photovoltaic moduledescribed in FIG. 5 can be the same as those described in FIG. 1.

FIG. 6 shows a sixth embodiment of the general method described above.Photovoltaic module 100 formed in this embodiment contains a pluralityof photovoltaic cells, each of which includes a substrate 110, a bottomelectrode 120, a photoactive layer 130, a hole carrier layer 140, and atop electrode 150. An insulator 160 is disposed between two neighboringphotovoltaic cells. The top electrode of one photovoltaic cell iselectrically connected to the bottom electrode of a neighboringphotovoltaic cell via an interconnecting electrically conductivematerial 170.

Photovoltaic module 100 shown in FIG. 6 can be prepared by five mainsteps as follows:

First, as shown in FIG. 6( a), a first electrically conductive layer122, a layer of a photoactive material (i.e., layer 132), a layer of ahole carrier material (i.e., layer 142), and a second electricallyconductive layer 152 are sequentially disposed (e.g., by using aliquid-based coating process) on substrate 110 to form an intermediatearticle.

Second, as shown in FIG. 6( b), the intermediate article can then betreated by a first laser ablation to form a plurality of discretephotovoltaic cells, in which first electrically conductive layer 122forms a plurality of bottom electrodes 120, layer 132 forms a pluralityof photoactive layers 130, layer 142 forms a plurality of hole carrierlayers 140, and second electrically conductive layer 152 forms aplurality of top electrodes 150. For example, the intermediate articlecan be treated to form a plurality of first cavities in firstelectrically conductive layer 122, layer 132, layer 142, and secondelectrically conductive layer 152. The first laser ablation can becarried out by irradiating the intermediate article with a first laser.In some embodiments, the first laser can have a wavelength that isprimarily absorbed by first electrically conductive layer 122, layer132, layer 142, and second electrically conductive layer 152, butsubstantially not absorbed by substrate 110. For example, the firstlaser can have a wavelength in the infrared (e.g., about 1,064 nm) orultra-violet region (e.g., about 355 nm).

Third, as shown in FIG. 6( c), a plurality of first insulators 160 canbe disposed in the first cavities formed in the second step above toelectrically insulate the photovoltaic cells.

Fourth, as shown in FIG. 6( d), the photovoltaic cells formed in thethird step above can then be treated by a second laser ablation to formsecond and third cavities in each photoactive layer 130, each holecarrier layer 140, and each top electrode 150. In some embodiments, thesecond laser can have a wavelength that is primarily absorbed byphotoactive layer 130, hole carrier layer 140, and top electrode 150,but substantially not absorbed by substrate 110 and bottom electrode120. For example, the second laser can have a wavelength in the visiblelight region, such as about 532 nm.

Finally, as shown in FIG. 6( e), interconnecting electrically conductivematerial 170 can then be disposed over each insulator 160 and into atleast a portion of each second cavity to electrically connect the topelectrode of one photovoltaic cell with the bottom electrode of aneighboring photovoltaic cell. Optionally, a second insulator (not shownin FIG. 6) can be disposed in each third cavity to ensure electricallyinsulation and to minimize short circuit between two neighboring cells.Photovoltaic module 100 thus formed include a plurality of photovoltaiccells that are electrically connected in series.

Other characteristics or aspects of the method and photovoltaic moduledescribed in FIG. 6 can be the same as those described in FIG. 1.

FIG. 7 shows a seventh embodiment of the general method described above.Similar to the photovoltaic module shown in FIG. 6, photovoltaic module100 formed in this embodiment contains a plurality of photovoltaiccells, each of which includes a substrate 110, a bottom electrode 120, aphotoactive layer 130, a hole carrier layer 140, and a top electrode150. Insulator 160 is disposed between two neighboring photovoltaiccells. Unlike the module shown in FIG. 6, an additional insulator 165 isdisposed between bottom electrode 120 and photoactive layer 130 at thelocation insulator 160 is deposited. The top electrode of onephotovoltaic cell is electrically connected to the bottom electrode of aneighboring photovoltaic cell via an interconnecting electricallyconductive material 170.

As shown in FIGS. 7( a) to 7(e), photovoltaic module 100 can be preparedin a manner similar to that shown in FIG. 6 above except that anadditional insulator 165 is disposed during the first step between firstelectrically conductive layer 122 and layer 132 at a location insulator160 is to be deposited. Without wishing to be bound by theory, it isbelieved that insulator 165 can further minimize short circuit betweentwo photoactive layers resulted from any debris generated duringtreatment the first electrically conductive layer (e.g., by laserablation). Photovoltaic module 100 thus formed includes a plurality ofphotovoltaic cells that are electrically connected in series.

While certain embodiments have been disclosed, other embodiments arealso possible.

In some embodiments, an electrically conductive layer can be irradiatedwith a laser from the side of the substrate on which a multilayer deviceis disposed. For example, electrically conductive layer 122 shown inFIG. 3( a) can be irradiated with a laser from the top of substrate 110.In such embodiments, the laser can have a wavelength such that it isprimarily absorbed by layer 122, but not substantially absorbed byinsulator 160. As a result, the laser reaches layer 122 by passingthrough insulator 160.

In some embodiments, an electrically conductive layer can be irradiatedwith a laser from the side of the substrate that is opposite to the sideon which a multilayer device is disposed. For example, electricallyconductive layer 122 shown in FIG. 3( a) can be irradiated with a laserfrom the bottom of substrate 110. In such embodiments, the laser canhave a wavelength such that it is primarily absorbed by layer 122, butnot substantially absorbed by substrate 110. As a result, the laserreaches layer 122 by passing through substrate 110.

In some embodiments, a photovoltaic cell in module 100 can include acathode as a bottom electrode and an anode as a top electrode. In someembodiments, a photovoltaic cell in module 100 can include an anode as abottom electrode and a cathode as a top electrode.

In some embodiments, a photovoltaic cell in module 100 can furtherinclude a hole blocking layer (not shown in FIGS. 1-7). Typically, thehole blocking layer is disposed between a photoactive layer and anelectrode at a side opposite to the hole carrier layer. For example, thehole carrier layer can be disposed between photoactive layer 130 andbottom electrode 120. In certain embodiments, some photovoltaic cells inmodule 100 include a hole blocking layer, while some photovoltaic cellsdo not include such a layer.

The hole blocking layer can generally be formed of a material that, atthe thickness used in a photovoltaic cell, transports electrons to anelectrode and substantially blocks the transport of holes to theelectrode. Examples of materials from which the hole blocking layer canbe formed include LiF, metal oxides (e.g., zinc oxide, titanium oxide),and amines (e.g., primary, secondary, or tertiary amines). Examples ofamines suitable for use in a hole blocking layer have been described,for example, in commonly-owned co-pending U.S. Application PublicationNo. 2008-0264488, the entire contents of which are hereby incorporatedby reference.

Without wishing to be bound by theory, it is believed that when aphotovoltaic cell includes a hole blocking layer made of amines, thehole blocking layer can facilitate the formation of ohmic contactbetween a photoactive layer and an electrode, thereby reducing damage tothe photovoltaic cell resulted from UV exposure.

Typically, a hole blocking layer can be at least 0.02 micron (e.g., atleast about 0.03 micron, at least about 0.04 micron, at least about 0.05micron) thick and/or at most about 0.5 micron (e.g., at most about 0.4micron, at most about 0.3 micron, at most about 0.2 micron, at mostabout 0.1 micron) thick.

In some embodiments, a photovoltaic cell in module 100 can includecertain layers shown in FIG. 1 in a reverse order. In other words, aphotovoltaic cell can include these layers from the bottom to the top inthe following sequence: a substrate, a bottom electrode, a hole carrierlayer, a photoactive layer, an optional hole blocking layer and a topelectrode.

While photovoltaic cells have been described above, in some embodiments,the methods described herein can also be used in manufacturing tandemphotovoltaic cells. Examples of tandem photovoltaic cells have beendescribed in, for example, commonly owned co-pending U.S. ApplicationPublication Nos. 2007-0181179 and 2007-0246094, the entire contents ofwhich are hereby incorporated by reference.

While photovoltaic cells electrically connected in series have beendescribed, in some embodiments, module 100 can also include photovoltaiccells electrically connected in parallel. For example, in a modulehaving two photovoltaic cells electrically connected in parallel, thefirst photovoltaic cell can include the layers in the order shown inFIG. 1, the second photovoltaic cell can include the hole carrier layerbetween the bottom electrode and the photoactive layer, and the topelectrode of the first photovoltaic cell can be electrically connectedto the bottom electrode of the second photovoltaic cell. In certainembodiments, some photovoltaic cells in module 100 can be electricallyconnected in series, and some of the photovoltaic cells in module 100can be electrically connected in parallel.

In some embodiments, the methods of preparing each layer (e.g., firstelectrically conductive layer 122, photoactive layer 130, hole carrierlayer 140, top electrode 150, insulator 160, and the interconnectingelectrically conductive material 170) in the photovoltaic cellsdescribed in FIGS. 1-7 can be readily incorporated in a continuousmanufacturing process, such as a roll-to-roll process, therebysignificantly reducing the time and cost of preparing a photovoltaiccell. Examples of roll-to-roll processes have been described in, forexample, commonly-owned U.S. Pat. No. 7,022,910 and commonly-ownedco-pending U.S. Application Publication Nos. 2005-0263179 and2005-0272263, the contents of which are hereby incorporated byreference.

While organic photovoltaic cells have been described above, other typesof photovoltaic cells can also be prepared by the methods describedherein. Examples of such photovoltaic cells include dye sensitizedphotovoltaic cells and inorganic photoactive cells with an photoactivematerial formed of amorphous silicon, cadmium selenide, cadmiumtelluride, copper indium selenide, and copper indium gallium selenide.In some embodiments, a hybrid photovoltaic cell can also be prepared bythe methods described herein.

While photovoltaic cells have been described above, in some embodiments,the compositions and methods described herein can be used to prepare aphotoactive layer in other electronic devices and systems. For example,they can be used prepare a photoactive layer in suitable organicsemiconductive devices, such as field effect transistors, photodetectors(e.g., IR detectors), photovoltaic detectors, imaging devices (e.g., RGBimaging devices for cameras or medical imaging systems), light emittingdiodes (LEDs) (e.g., organic LEDs or IR or near IR LEDs), lasingdevices, conversion layers (e.g., layers that convert visible emissioninto IR emission), amplifiers and emitters for telecommunication (e.g.,dopants for fibers), storage elements (e.g., holographic storageelements), and electrochromic devices (e.g., electrochromic displays).

The following example is illustrative and not intended to be limiting.

EXAMPLE Fabrication of Photovoltaic Modules

A mechanically-scored 5-lane photovoltaic module (i.e., containing 5photovoltaic cells) and a laser-scored 5-lane photovoltaic module werefabricated as follows: An ITO coated PET substrate was first scored withby using laser ablation or mechanical scribing to form 5 lanes on thesubstrate. The scored substrate was cleaned by sonicating in isopropanolfor 10 minutes. A 0.5% solution of cross-linkable organic material inbutanol was blade coated onto the ITO at a speed of 5 mm/s at 80° C. toform an electron injection layer. A semiconductor blend of P3HT and PCBMin a mixture of tetralene and xylene was blade coated onto the electroninjection layer at a speed of 40 mm/s at 65° C. and was dried to form aphotoactive layer. Next, a polythiophene-based hole transport layer wasblade coated onto the photoactive layer at a speed of 7.5 mm/s at 65° C.The whole stack was then annealed in a glove box at 140° C. for 5minutes. A 5-lane photovoltaic module was then formed by thermallyevaporated a layer of 300-nm silver thin film under a vacuum of 10⁻⁶torr.

The performance of the mechanically-scored and laser-scored photovoltaicmodules prepared above was measured and summarized in Table 1 below.

TABLE 1 PV Parameters Eff Voc Jsc Vmax FF Units % V mA/cm² V N/AMechanically-Scored 2.59 0.538 8.74 0.4 0.55 Modules Laser-ScoredModules 2.55 0.537 8.88 0.39 0.535

The results showed that the laser-scored photovoltaic module exhibited aperformance similar to that of the mechanically-scored photovoltaicmodule.

Other embodiments are in the claims.

What is claimed is:
 1. A method, comprising: forming a first multilayerdevice on a transparent substrate, the first multilayer devicecomprising a first electrically conductive layer and a photo activelayer, the first electrically conductive layer being between the photoactive layer and the substrate; and after forming the first multilayerdevice, treating the first electrically conductive layer to form aplurality of discrete electrodes by forming a plurality of cavities sothat each discrete electrode is separated from another discreteelectrode by a cavity, thereby converting the first multilayer deviceinto a first photovoltaic cell.
 2. The method of claim 1 wherein thesubstrate is electrically non-conductive.
 3. The method of claim 1wherein the substrate comprises a polymer.
 4. The method of claim 1wherein the substrate comprises a polymer selected from the groupconsisting of a polyethylene terephthalate, a polyimide, a polyethylenenaphthalate, a polymeric hydrocarbon, a cellulosic polymer, apolycarbonate, a polyamide, a polyether, and a polyether ketone.
 5. Themethod of claim 1 wherein the substrate comprises a fluorinated polymer.